1. Field of the Invention
The present invention relates to a photographic film take-up device for taking up a photographic film into a cartridge main body when a photographic film cartridge is assembled.
2. Description of the Related Art
A cartridge for 135 type photographic film, which is the most widely used photographic film, is formed of a cartridge main body structured by a cartridge body, which is a thin metal plate formed into a cylindrical shape, and two caps. A spool on which the photographic film is wound is accommodated in the cartridge. Japanese Patent Application Publication No. 2-691 discloses a method of assembling such a photographic film cartridge in which a photographic film which has been taken up on a spool is placed into the cartridge main body by operations carried out in a dark room. Further, as disclosed in Japanese Patent Application Publication No. 60-48748, a cartridge main body which is assembled once is separated into portions at a photographic film incorporation station within a dark room. A spool on which a photographic film has been wound is inserted therein, and the cartridge main body is then reassembled.
Moreover, in Japanese Patent Application Laid-Open Nos. 49-107732 and 52-77723, a cartridge main body having an empty spool is formed in a light room. A tongue-shaped guide plate is inserted into a film path formed in the cartridge main body. The photographic film is inserted into the cartridge main body from the trailing end portion thereof with the guide plate serving as a guide. After the trailing end portion of the photographic film engages with the spool, the spool is rotated so that the photographic film is taken up in the cartridge main body.
In accordance with the specifications of U.S. Pat. Nos. 4,834,306 and 4,846,418 as well as Japanese Patent Application Laid-Open No. 3-37645, the cartridge main body is assembled as a resin product, and a photographic film cartridge having the function of delivering the photographic film out of the cartridge main body due to the rotation of the spool is disclosed. These photographic film cartridges differ from their predecessors in so far as the leader portion of the photographic film does not protrude from the cartridge main body regardless of whether the photographic film is unused or has been used. The photographic film can thus be more reliably accommodated so as to be shielded from light, and the handling of these photographic film cartridges before and after use thereof is easy.
An example of a conventional photographic film take-up method and the main portions of a photographic film take-up device will be described hereinafter with reference to FIGS. 10 through 16 as an application of the technology of the above-mentioned cartridges. As illustrated in FIGS. 10 through 12, a spool 2 is provided so as to be freely rotatable within a cartridge main body 1. A slit 3 for insertion of a photographic film F is formed in an outer circumferential surface of the spool 2. Further, a slit-shaped film path 4 is formed in the cartridge main body 1. A cover member 6 is provided between the film path 4 and a film accommodating portion 5 within the cartridge main body 1 so as to be freely openable and closable.
As shown in FIG. 13, a pair of flanges 11a are formed integrally with the spool 2, and the photographic film F is wound around a shaft portion 11b of the spool 2. Both ends of the spool 2 are exposed at the side surfaces of the cartridge main body 1, and keys 12 are provided at the exposed portions. When the spool 2 is rotated, the keys 12 engage with a member for driving the spool.
The slit 3 is formed in the shaft portion 11b. A pair of pawls 13 and presser ribs 14 are provided at an interior portion of the slit 3. The presser ribs 14 project between the pawls 13.
A pair of engagement holes 15 are formed in the trailing end portion of the photographic film F. When the photographic film F is taken up, the engagement holes 15 are engaged by the pawls 13 due to a pair of arms 21 and a pawl plate 22 which will be described later. After engagement, the trailing end of the photographic film F is pressed by the presser ribs 14 so that the trailing end does not rise up. Therefore, the engagement of the pawls 13 and the engagement holes 15 is maintained. Even if force is applied in a direction of pulling the photographic film F out from the slit 3, the photographic film F is not pulled out therefrom.
A pair of holes 16 are formed in the trailing end of the photographic film F at positions at the outer sides of the engagement holes 15. The holes 16 are used when the trailing end of the photographic film F is inserted into the slit 3.
When the photographic film F is taken up, the cartridge main body 1 is fixed at a take-up device, and the photographic film F which is supplied from a film guide 23 is taken up thereon. The pair of arms 21 and the pawl plate 22 are used in the taking-up of the photographic film F.
Namely, the pair of arms 21 are respectively connected to a mounting plate and rotate reciprocally around a shaft 24 due to an unillustrated stepping motor or the like. The pawl plate 22 is formed by a thin metal plate which is curved into a circular arc shape, and a pair of pawls 25 are provided at the end thereof.
As illustrated in FIG. 10, when the photographic film F is delivered from the film guide 23, the pair of arms 21 rotates in a counterclockwise direction synchronously with the delivery of the photographic film F, so that the pawls 25 engage the holes 16. In this state, when the pair of arms 21 continues to rotate, as illustrated in FIG. 11, the trailing end of the photographic film F becomes integral with the pawl plate 22 and enters into the film accommodating portion 5 from the film path 4. Next, as illustrated in FIG. 12, the trailing end portion of the photographic film F enters into the spool 2 from the slit 3.
As a result, the engagement holes 15 engage the pawls 13, and the trailing end of the photographic film F is engaged with the spool 2. Subsequently, the pair of arms 21 is rotated in a clockwise direction so that the pawls 25 are removed from the holes 16. The pawl plate 22 is removed to the exterior of the cartridge main body 1, and the spool 2 is rotated in the counterclockwise direction so that the photographic film F is taken up. The rotation of the spool 2 is effected by the keys 12 engaging the members for driving.
As illustrated in FIG. 14, the pawls 25 engage the two holes 16, and the trailing end of the photographic film F is guided to the spool 2 while both sides of the trailing end are pulled. At this time, because the photographic film F is being pulled at two places, i.e., the two sides, as illustrated in FIG. 15, the central portion of the photographic film F swells and curls into a trough shape.
If this type of a trough shape is formed, when the photographic film F is guided to the spool 2 and inserted into the slit 3, as illustrated in FIG. 16, the portion which is curled into a trough shape abuts the shaft portion 11b of the spool 2 and cannot be inserted into the slit 3. In this case, the engagement holes 15 cannot be engaged by the pawls 13, and the photographic film F cannot be taken up.
When the photographic film F is to be taken up, it is preferable that the width of the slit 3 be narrow in consideration of the conveyability of the film when the film is pulled out from the cartridge main body 1 for use.
However, when a trough-shape curl is formed in the photographic film F as described above, if the width of the slit 3 is narrow, it is even more difficult than described above for the photographic film F to be taken up. In order to improve the conveyability of the film, a highly precise insertion operation is needed in a case in which the gap of the slit 3 of the spool 2 is narrow. Therefore, there is a need to avoid the interference between the spool and the film as described above.